From the guy that brought you Stereo Tool comes Perfect Declipper.

 It does make tracks sound clearer.

Loudness War

I'm not an expert in audio signals, but light encoding signals (photography) shares some aspects in common with other kind of signals encoded digitally.

What is seen in that video looks to me simply impossible, a fake. Audio signal of a particular song is never a pure sine wave (or a mix of various sine waves), so it's impossible to reconstruct it when is clipped, because of a simple reason: you can not estimate how the signal will be if you don't know it's original shape.

It's the same reason for photography: when a subject is overexposed, it becomes pure plain white, and it's impossible to deconstruct it, except if you assume the subject is *pure* *plain* (put here any color). This means that it should be absolutely, completely plain, without even one small dot of another color. And that's even a hard task to achieve when using plain white background in a pro photo studio, so real objects are almost never pure plain tone.

anyway, thanks for the info, plop. Very curious.

I agree with you in that If you blow out an image save that, and then try to reconstruct the original image it is not possible to get back the information that was thrown out. That is is an extreme example. What this software does is more liken to applying the sharpen filter in Photoshop. Even sometimes when using Photoshop with some filters less is more.

However with this tool we are all free to download and try it. So go on and give it a go and see for yourself if it improves dynamically any poorly mastered music that you have. I have been pleasantly surprised with some really atrocious recordings and how they turned out after being rinsed through Perfect Declipper.

Also somewhere on his website, he offers the files for you try and declip yourself rather than just relying on the you tube video where some sceptical people have suggested that they may be faked.

it just adds compression from what my ears hear

you can't "undo" clipping - the guy says in the description it uses information gathered from the signal before and after clipping - well that is just "fudging"

I'm gonna try it out on some beasted out video clips

Usually the conversion to mp3 clips awfully the tracks, if additional "expert" settings are used. The original tracks are mastered by professionals (i-m not talking about garage band demos) and it-s hard for me to believe that they do not mean business.

It is clear to me that the examples above were chosen to illustrate the power of the plugin, and are not the original tracks. My red hot chilly peppers cd does not sound like that. Wondering anyway how good is his "guessing" algorithm.

I prefer having the original cd, sometimes even copying the cd to another cd via image breaks the sound and makes it loose detail. I cannot explain that, it-s just what I feel.

Anyway, for 99% of listeners, that will not make a difference, because it would pass unnoticed without the proper hifi equipment and a trained ear. I even wonder if I still hear the same as 10 years ago.

My dad listens to his music with deranging settings for high frequencies, however that doesn't seem to bother him, even if for me it is unbearable. My guess is that he doesn't even hear all those frequencies.

Well I dug out a copy of RHC's Californication.

This is a screen grab as it was processing. I've set the attenuation to x1.00 and the input level to just under 1/2 the maximum so that you can easily see the differences immediately. The four green bars represent the levels of the music, with the top two the input and the bottom two the output. You can see below that the input levels have reached the maximum ie clipping. The lower two output bars extend beyond this maximum input level. This is what the plugin has predicted what would have been clipped off. The top spectral graphic shows the input and the red lines indicate where the clipping has been detected. The lower spectral graphic shows the then corrected output.

Hans van Zutphen has added some mathematical algorithm to predict the missing information (the rate of which can be adjusted). Granted it won't perform miracles as to get proper dynamic range back would need the original master tapes, but what you get when hearing Californication is slightly more dynamic range, rather than the constant brick wall ear blasting from the original during the louder sections of the song causing listener fatigue.

For the majority of tracks (read older mastered music c. 1990s) this plugin has minimal effect, but for newer stuff mastered at a constant loud "radio ready" level, it will help make it more bearable to listen to. Certainly a useful defensive tool in the aptly named "loudness war".

As an aside, the same developer Hans van Zutphen created Stereo Tool to compress audio for the purpose of listening to it "hot" via the radio. Suitable for blasting out via speakers, but extremely hard on the ears when listening to with 'phones.

I downloaded a demo version of the Perfect Declipper vst plugin suitable for use with Audacity today and ran Red Hot Chilli Pepper's Californication through it.

This is how it looked before it was processed. In glorious clipped super loud mode, as per by the record company.

This is how it now looks after being processed with the Perfect Declipper plugin.

I know which one is going to be more easier on my ears.

There are couple of quiet parts at 2:30 and 5:00, this is due to a recorded message being introduced into the demo version of the plugin. Some beeps are also introduced into the demo version of the plugin, but not noticeable above.

interesting stuff .

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@Plop,

I'd like to give what you did a try, but am having difficulties. I have audacity installed, and have downloaded the .dll file of perfect declipper, and put it in the same folder as the lame_enc.dll and others. How can I then load an audio file into audacity and run the perfect declipper on it? Any help appreciated